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Contributions à la simulation numérique des modèles de Vlasov en physique des plasmasCrouseilles, Nicolas 14 January 2011 (has links) (PDF)
To be
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Nodal configurations and Voronoi tessellations for triangular spectral elementsRoth, Michael James 07 October 2005 (has links)
By combining the high-order accuracy of spectral expansions with the locality and
geometric flexibility of finite elements, spectral elements are an attractive option for
the next generation of numerical climate models. Crucial to their construction is the
configuration of nodes in an element — casual placement leads to polynomial fits
exhibiting Runge phenomena manifested by wild spatial oscillations. I provide highorder
triangular elements suitable for incorporation into existing spectral element
codes. Constructed from a variety of measures of optimality, these nodes possess the
best interpolation error norms discovered to date.
Motivated by the need to accurately determine these error norms, I present an
optimization method suitable for finding extrema in a triangle. It marries a branch
and bound algorithm to a quadtree smoothing scheme. The resulting scheme is both
robust and efficient, promising general applicability.
In order to qualitatively evaluate these nodal distributions, I introduce the concept
of a Lagrangian Voronoi tessellation. This partitioning of the triangle illustrates the
regions over which each node dominates. I argue that distant and disconnected regions
are undesirable as they exhibit a non-physical influence.
Finally, I have discovered a link between point distributions in the simplex and
on the hypersphere. Through a simple transformation, a distance metric is defined
permitting the construction of Voronoi diagrams and the calculation of mesh norms.
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Methodology to analyse three dimensional droplet dispersion applicable to Icing Wind TunnelsSorato, Sebastiano January 2009 (has links)
This dissertation presents a methodology to simulate the dispersion of water droplets in
the air flow typical of an Icing Tunnel. It is based on the understanding the physical
parameters that influence the uniformity and the distribution of cloud of droplets in the
airflow and to connect them with analytical parameters which may be used to describe
the dispersion process. Specifically it investigates the main geometrical and physical
parameters contributing to the droplets dispersion at different tunnel operative
conditions, finding a consistent numerical approach to reproduce the local droplets
dynamic, quantifying the possible limits of commercial CFD methods, pulling out the
empirical parameters/constant needing to simulate properly the local conditions and
validating the results with calibrated experiment.
An overview of the turbulence and multiphase flow theories, considered relevant to the
Icing Tunnel environment, is presented as well as basic concepts and terminology of
particle dispersion. Taylor’s theory of particle dispersion has been taken as starting
point to explain further historical development of discrete phase dispersion. Common
methods incorporated in commercial CFD software are explained and relative
shortcomings underlined. The local aerodynamic condition within tunnel, which are
required to perform the calculation with the Lagrangian particle equation of motions,
are generated numerically using different turbulent models and are compared to the
historical K-ε model. Verification of the calculation is performed with grid
independency studies. Stochastic Separated Flow methods are applied to compute the
particle trajectories. The Discrete Random Walk, as described in the literature, has been
used to perform particle dispersion analysis. Numerical settings in the code are related
to the characteristics of the local turbulent condition such as turbulence intensity and
length scales. Cont/d.
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The Effects of Substrate Heterogeneity on Colloid DepositionKemps, Jeffrey A L 06 1900 (has links)
Heterogeneity of surfaces is often included in mathematical treatments of colloid transport and deposition as an afterthought, if at all. Most previous models of colloid transport and deposition have employed idealizations and simplifications such as assuming smooth collector surfaces with uniform chemical properties. This research proposes a new heterogeneous interaction model (HIM) to account for colloidal forces between particles and heterogeneous substrates. Extending the approach employed with the HIM, the inclusion of convection and diffusion in the model leads to a Lagrangian particle tracking model (PTM) for predicting colloid transport and deposition on a planar substrate containing one or more protruding asperities in the presence of shear flow. An important part of the PTM is an accurate rendering of the fluid flow field around the model substrate, which is obtained from a numerical solution of the Stokes equations. A simple approximation of the particle-substrate hydrodynamic interactions was developed for the PTM based on the universal hydrodynamic correction functions. This model was employed to quantitatively predict how presence of asperities on a collector can influence the deposition of particles on the substrate in shear flow. Flow field modifications due to the substrate's physical heterogeneity -- coupled with hydrodynamic interactions -- and the lateral migration (colloidal) forces near chemically heterogeneous substrates yield remarkably diverse deposition probabilities and deposit morphologies. The general approach of this research, which involves the use of the HIM in conjunction with the Brownian PTM, results in the first simulation tool of its kind to attempt to quantify deposition on heterogeneous substrates.
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A finite element method for ring rolling processesDewasurendra, Lohitha. January 1998 (has links)
Thesis (Ph. D.)--Ohio University, June, 1998. / Title from PDF t.p.
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Energy and momentum conservation in Bohm's Model for quantum mechanicsHall, Bryan. January 2004 (has links)
Thesis (Ph. D.)--University of Western Sydney, 2004. / Includes bibliographical references.
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A modified shifting bottleneck approach to job shop scheduling with sequence dependent setups (MSBSS) /Sun, Xiaoqing, January 1997 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 119-128). Also available on the Internet.
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Spacecraft formation flight at sun-earth/moon libration pointsTolbert, Douglas Robert, January 2009 (has links) (PDF)
Thesis (Ph. D.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 14, 2009) Includes bibliographical references (p. 68-71).
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A modified shifting bottleneck approach to job shop scheduling with sequence dependent setups (MSBSS)Sun, Xiaoqing, January 1997 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 119-128). Also available on the Internet.
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Multi-beam-interference-based methodology for the fabrication of photonic crystal structuresStay, Justin L. January 2009 (has links)
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Thomas K. Gaylord; Committee Member: Donald D. Davis; Committee Member: Gee-Kung Chang; Committee Member: Muhannad S. Bakir; Committee Member: Phillip N. First. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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